The paper explores the notion of "the subject" in the context of education as an alternative to more limited concepts such as the student or learner. Drawing on the thought of Cornelius Castoriadis, the subject under consideration is a conscious, self-reflective subject that organizes and modifies itself in relation to a world of significations. Through the capacity for conscious self-modification, the subject becomes a self-reflective agent in a socially instituted world of significations. For Castoriadis, this kind of subjectivity is not readily available in every kind of social organization; rather, it is a possible product of a society that has instituted itself explicitly or autonomously. This socially instituted reflexivity is for Castoriadis historically associated with democracy, politics and philosophy. In the second part, the discussion is extended to the non-human realm and the world of the living being. Here, too, meaning--or proto-meaning in the case of the living being--is a constituent in the formation of a world. In this discussion, where Francisco Varela is an important source, concepts such as meaning, signification, normativity and purpose are introduced in the natural sciences, or rather, the sciences of human and non-human nature. The aim of the paper is twofold: on the one hand, to introduce pedagogical reflections into discussions about human on non-human nature; and, on the other, to develop a richer conceptual repertoire for exploring educational phenomena than what is immediately available. An important background, in both cases, is the possibility of ecological crisis, which poses new problems for educators.